Abstract: AMP-activated protein kinase (AMPK) functions as a key energy sensor and metabolic rheostat to maintain cells' energy needs, largely through maintaining ATP levels. Disruption of AMPK signaling leads to neuronal death, while mutations in human AMPK subunits cause the fatal cardiac disorder, Wolff-Parkinson-White syndrome. We are using a genetic model in Drosophila to identify genes that modulate AMPK signaling in vivo. Using this novel forward genetic screen we have identified nucleoside diphosphate kinase (NDPK) as a potential modifier and target of AMPK signaling. We have found a new mechanism whereby AMPK-dependent phsphorylation of NDPK turns it off. This off switch site corresponds to a location mutated in advanced human neuroblastoma. Through identification of new genes that suppress AMPK RNAi lethality, and making a genetic model of mutations in AMPK that cause human disease, we hope to identify both new mechanisms and molecules that modulate AMPK function in vivo.